A354837 - OEIS

A354837

Odd numbers k such that gcd(k, A007088(k)) != 1.

21, 33, 63, 69, 81, 99, 111, 123, 159, 165, 183, 189, 203, 207, 219, 231, 237, 243, 249, 259, 261, 273, 297, 303, 315, 321, 363, 399, 411, 423, 429, 435, 441, 459, 483, 489, 495, 513, 543, 561, 567, 573, 585, 591, 603, 615, 621, 627, 633, 663, 669, 693, 707, 711

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..54.

EXAMPLE

k = 33; gcd(33,A007088(33)) = gcd(33, 100001) = 11, thus k = 33 is a term.

MATHEMATICA

Select[Range[1, 700, 2], ! CoprimeQ[#, FromDigits[IntegerDigits[#, 2]]] &] (* Amiram Eldar, Jun 08 2022 *)

PROG

(PARI) isok(k) = (k%2) && (gcd(k, fromdigits(binary(k))) != 1); \\ Michel Marcus, Jun 09 2022

CROSSREFS